Thiabendazole degrading enriched bacterial consortium Metagenome

Recalcitrant to degradation compounds used in agriculture pose a challenge for environmental management. Thiabendazole (TBZ), a benzimidazole commonly used protectively against postharvest fungal diseases and as anthelminthic in livestock farming, is highly stable (DT50 > 1-2 years) in the environment without previously known potent biodegraders. Our group has recently enriched from soil a bacterial consortium able to rapidly degrade TBZ through cleavage of the benzimidazole ring and degradation of the resulting benzyl and thiazole ring moieties. However, no pure TBZ-degrading isolate was obtained suggesting complex interactions between consortium members. We employed an “omics” approach to elucidate the microbial interactions that maintain the degradation consortium capability. Metagenome sequencing at various conditions resulted in binning 16 genomes with 84-93% completeness. These together with stable isotope probing (SIP)-amplicon sequencing of the 16S rRNA gene verified previous group findings of the key degrading role of a Sphingomonas strain comprising the most dominant metagenome bin. In a time-series experiment, RNA sequencing of the consortium supplied with TBZ or succinate as sole carbon showed the enhanced expression by the suspect degrader of: a highly versatile genetic armory for aromatic compound degradation; signaling and transport associated genes; secretory and conjugative system activities. Networking analysis suggested the interaction of Sphingomonas with a Hydrogenophaga strain and possible contribution of the latter to the overall cobalamin balance. Correlations among consortium member 16S rRNA gene relative abundances further support potential auxotrophy. On-going metabolomics and proteomics analysis will further elucidate underlying interactions and mechanisms and will be presented at the meeting.